Not to be confused with Hartsburg, a similarly-named settlement also in Boone County.
Harrisburg is located on Missouri Route 124 about one mile from the Boone-Howard county line. Fayette is about eleven miles to the west and U.S. Route 63 is about seven miles to the east along route 124. Perche Creek flows past two miles east of the community.
According to the United States Census Bureau, the village has a total area of 0.76 square miles (1.97 km), of which 0.75 square miles (1.94 km) is land and 0.01 square miles (0.03 km) is water. The town is located between the Moniteau and Perche watersheds. The Prairie fork of the Moniteau heads towards Harrisburg, as does the Callaham fork of Perche Creek.
As of the census of 2010, there were 266 people, 101 households, and 74 families residing in the village. The population density was 354.7 inhabitants per square mile (137.0/km). There were 121 housing units at an average density of 161.3 per square mile (62.3/km). The racial makeup of the village was 97.0% White, 0.4% African American, 0.4% Native American, and 2.3% from two or more races. Hispanic or Latino of any race were 0.4% of the population.
There were 101 households of which 43.6% had children under the age of 18 living with them, 55.4% were married couples living together, 13.9% had a female householder with no husband present, 4.0% had a male householder with no wife present, and 26.7% were non-families. 25.7% of all households were made up of individuals and 10.9% had someone living alone who was 65 years of age or older. The average household size was 2.63 and the average family size was 3.12.
The median age in the village was 29.8 years. 33.5% of residents were under the age of 18; 7.9% were between the ages of 18 and 24; 31.9% were from 25 to 44; 17.3% were from 45 to 64; and 9.4% were 65 years of age or older. The gender makeup of the village was 45.9% male and 54.1% female.
As of the census of 2000, there were 184 people, 77 households, and 50 families residing in the town. The population density was 265.7 people per square mile (103.0/km²). There were 86 housing units at an average density of 124.2 per square mile (48.1/km²). The racial makeup of the town was 95.65% White, and 4.35% from two or more races.
There were 77 households out of which 32.5% had children under the age of 18 living with them, 50.6% were married couples living together, 13.0% had a female householder with no husband present, and 33.8% were non-families. 31.2% of all households were made up of individuals and 16.9% had someone living alone who was 65 years of age or older. The average household size was 2.39 and the average family size was 2.96.
In the town the population was spread out with 25.5% under the age of 18, 10.3% from 18 to 24, 26.6% from 25 to 44, 22.8% from 45 to 64, and 14.7% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 95.7 males. For every 100 females age 18 and over, there were 80.3 males.
The median income for a household in the town was $40,714, and the median income for a family was $44,167. Males had a median income of $30,000 versus $24,375 for females. The per capita income for the town was $14,298. About 12.0% of families and 18.0% of the population were below the poverty line, including 28.8% of those under the age of eighteen and 25.0% of those sixty five or over.